In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Try to find the best answer that is most likely to fill in "_". Note that the URLs in the text have been replaced with [Link].

Washington (CNN) Secretary of State Rex Tillerson said that the US is willing to sit down for talks with North Korea, but only if it relinquishes its pursuit of nuclear weapons. Tillerson, speaking at the State Department press briefing, stressed that the US was not seeking regime change or looking to send its military "north of the 38th parallel" that divides North and South Korea. But he emphasized that the danger posed by Pyongyang, which test fired two intercontinental ballistic missiles in July, was unacceptable. "We do not seek regime change. We do not seek an accelerated reunification of the peninsula. We do not seek an excuse to send our military north of the 38th parallel," Tillerson said during a surprise visit to the agency's briefing room on Tuesday.Secretary of State Tillerson spoke at the press briefing for the first time"We are not your enemy," Tillerson said, speaking to North Korea directly 
 Question:Tillerson said the threat from _ has "materialized in the ways we expected it would" and that the administration's first response has been to initiate "a sustained and continued intensified campaign of what I like to call peaceful pressure."
North Korea